Half to eittee



(N0 Model.)

J. W. SHAVER.

CENTER FOR TUR N TABLES ANDBRIDGES. No. 323,743. Patented Aug 4 1885.

TI! 3 9 ,3 uri i 1 -1 E J 1 WITNESSES:\

' .UNITED STATES PATENT ()rrrcai.

JOHN WV. SEAVER, OF PITTSBURG. TENNSYLVANIA, ASSIGNOR OF ONE- I HALF TOBITTER & OONLEY, OF SAME PLACE.

CENTER FOR TURN-TABLES AND BRIDGES.

JPECIFICATION Forming part; of Letters Patent No. 323,743, dated August4, 1885.

(So model.)

To all whom, it may concern:

Be it known that I, JOHN W. SEAVER. of Pittsburg, in the county ofAllegheny and State of Pennsylvania, have invented certain new anduseful Improvements in Centers for Turn-Tables and Bridges, of which thefollowing is a specification.

The object of my invention is to provide a center for turn-tables orpivot-bridges which shall present the advantages of simplicity andeconomy of construction, readiness and convenience of adjustment fordifferent desired heights, capacity of permitting free longitudinalvibrating movement of the structure which it supports while insuringtransverse steadiness thereof, and concentration of the weight of thestructure upon a single central support in such manner as to avoidunequal distribution of load over the bearing-surfaces, and to dispensewith the series of sustaining-bolts heretofore usually employed.

To this end my invention, generally stated, consists in the combination,in a turntable or pivot-bridge, ofa central pivot and a collaradjustable vertically thereon, said collar forming a support or bearing,upon which the turntable rests wit-h the capacity of longitudinalvibration, and on which it is fixed as against lateral movement.

The improvements claimed are hereinafter more fully set forth.

In the accompanying drawings, Figure 1 is a transverse central sectionthrough a turntable embodying my invention, and Fig. 2 a longitudinalcentral section through a portion of the same, the center being shown inelevation.

In the practice of my invention the two main girders 1 1 of a turn-tableor pivot-bridge are connected one to the other by two crossgirders, 2 2,which are located at right angles to the main girders, adjacent to andat equal distances from the transverse central plane of the latter, andthe cross-girders 2 2 are in turn connected near their upper sides bytwo bearing-beams, 3 3,which extend parallel with the main girders onopposite sides of and at equal distances from the longitudinal centralplane of the turn-table, each of said bearingbeams having a bearing, 4,secured to its lower side, said bearings being segmentally recessed ontheir lower faces concentrically with the transverse central plane ofthe table. An adjusting-collar, 5, provided withtwodiametrically-oppositejournalsorrockerprojections,6, which fit t'reelwithin the recesses of the bearings 4, is fitted with the capacity ofvertical movement upon a central pivot, 7, the lower end of which restswithin astep or bearing, 8, which is secured to a suitable foundationand about the axis of which the table rotates in operation. The collar 5is adjustable vertically upon the pivot 7, and such adjustment may beeffected either by means of a screwthread formed upon the pivot andengaging a corresponding internal thread on thecollar, as shown in thedrawings, or in any other suitable manner,.as bythe interposition ofcollars or washers between the adjusting collar and step. The pivot 7may bear directly upon the step by a plain face, asshown,or may besupported upon a series of conical rollers located in a recess on thetop of the step, in order to diminish the friction of the load thereon.Axial movement of the pivot relatively to the bearing-beams and adjusting-collar is prevented by a stop-plate, 9, located between andfitting at its ends against the inner sides of the bearing-beams 3, saidplate being removably connected to the pivot 7 in any manner proper toprevent rotation of the latter independently of the plate. In theinstance shown a squared central projection on the bottom of the stopplate fits into a corresponding recess on the top of the pivot; but,ifpreferred, the pivot may pass through an opening in the stop-plate andbe prevented from rotating therein by a key engaging slots in thesurface of contact, or by being flattened or squared on one or moresides in correspondence with the opening through which it passes.

To effect the vertical adjustment of the turntable orbridge thestop-plateis removed from the pivot, and a wrench or key being appliedto the latter it is turned in one or the other direction while the tableis held against rotation, according as it is desired to raise orlowerthe table, until the latter is brought to the proper level by thelongitudinal movementof the adjusting-collar 5 on the pivot 7, when thestop-plate is replaced, and the collar thereby lockedin position at theheight desired. It will be obvious that a corresponding result may beeffected by turning the table around the pivot while the latter is heldstationary. In the case where the pivot is not threaded and adjustmentis made by means of washers, the turn-table is jacked or otherwiseraised to the desired height, and such a number or thickness of washersinserted under the collar as may beproper to maintain it thereat.

it will be seen that my improvements are readily applicable atcomparatively small expense to turntables or pivot-bridges of any of theordinary constructions, and that in their operation the height of thetable or bridge may be quickly and accurately adj usted to any desiredlevel. Free longitudinal vibra ion is permitted by the bearings androcker projections on which they rest without liability to lateralmovement, and the entire load is transferred to and borne by a singlecentral step or hearing.

I am aware that a central pivot provided with a screw-thread engaging anut fixed to the center crossbeam of a turn-table so as to admit ofvertical adjustment of the table rel atively to the pivot was known inthe art at thcdatc of my invention, and such construc tion, broadly,ldiselatim. My invention, however, ditl'ers therefrom in the essentialparticular of admitting of required longitudinal vibration of the tableupon the pivot, which, so far as my knowledge and information extends,is not provided for in constructions of the character above referred to.

{claim herein as my invention and desire i to secure by Letterslatent 1. The combination, in a turn-table or pivot-bridgc, of a centralpivot, acollar mounted and capable of vertical adjustment thereon,journals fixed upon said collar in the transverse central plane of themain supportinggirders, and bearings connected to said girders andresting upon said journals, substantially as set forth.

2. The combination, in a turn-table or pivot-bridge, of a central pivot,a collar mounted with the capacity of vertical adj ustmcnt thereon,bearings connected to the main supporting girders and resting uponjournals on the collar, and a removable stop-plate connected to thepivot and abutting against lJOtll'lllg-Sllffaces fixed to the maingirders, so as to prevent rotation of thepivot independently there 0t,substantially as set forth.

3. The combination, in a turn-table or piv-' ot-bridge, ot'a pair ofmain girders, a pair of cross-gt rders secured thereto, a pat r ofbearing bars connecting the crossgirders on opposite sides oftheirlongitudinal central plane, bearings which are segmental] y recessed ontheir lower sides and secured to the bearing-bars with their recessesconcentric with the transverse central plane thereof, a central pivothaving an external screw-thread and fitting in a stop or hearing, acollar having an internal central thread engaging the thread of the pivet, and apair of journals fitting freely in the bearings, and aremovable stop-plate connected to the pivot and fitting at its endsagainst the bearing-bars, substantially as set forth.

JOHN W. SEAVER.

Witnesses:

W. SHEPARD, JNO. F. (l. \VALDO.

